Portable and simultaneous detection of four respiratory pathogens through a microfluidic LAMP and real-time fluorescence assay.

Respiratory pathogen infections are seasonally prevalent and are likely to cause co-infections or serial infections during peak periods of infection. Since they often cause similar symptoms, simultaneous and on-site detection of respiratory pathogens is essential for accurate diagnosis and efficient treatment of these infectious diseases. However, molecular diagnostic techniques for multiple pathogens in this field are lacking. Herein, we developed a microfluidic LAMP and real-time fluorescence assay for rapid detection of multiple respiratory pathogens using a ten-channel microfluidic chip with pathogen primers pre-embedded in the chip reaction well. The microfluidic chip provided a closed reaction environment, effectively preventing aerosol contamination and improving the accuracy of the detection results. Its corresponding detection instrument could automatically collect and display the fluorescence curve in real time, which was more conducive to the interpretation of results. The results showed that the developed method could specifically recognize the nucleic acid of influenza A(H1N1), Mycoplasma pneumoniae, respiratory syncytial virus type A, and SARS-CoV-2 with low detection limits of 104 copies per mL or 103 copies per mL. The test results on clinical samples demonstrated that the developed method has high sensitivity (92.00%) and high specificity (100.00%) and even has the capability to differentiate mixed-infection samples. With simple operation and high detection efficiency, the present portable and simultaneous detection assay could significantly improve the efficiency of on-site detection of respiratory infectious diseases and promote the accurate treatment, efficient prevention and control of the diseases.

Prevalence and genetic basis of Mycobacterium tuberculosis resistance to pretomanid in China.

BACKGROUND: Pretomanid is a key component of new regimens for the treatment of drug-resistant tuberculosis (TB) which are being rolled out globally. However, there is limited information on the prevalence of pre-existing resistance to the drug. METHODS: To investigate pretomanid resistance rates in China and its underlying genetic basis, as well as to generate additional minimum inhibitory concentration (MIC) data for epidemiological cutoff (ECOFF)/breakpoint setting, we performed MIC determinations in the Mycobacterial Growth Indicator Tube™ (MGIT) system, followed by WGS analysis, on 475 Mycobacterium tuberculosis (MTB) isolated from Chinese TB patients between 2013 and 2020. RESULTS: We observed a pretomanid MIC distribution with a 99% ECOFF equal to 0.5 mg/L. Of the 15 isolates with MIC values > 0.5 mg/L, one (MIC = 1 mg/L) was identified as MTB lineage 1 (L1), a genotype previously reported to be intrinsically less susceptible to pretomanid, two were borderline resistant (MIC = 2-4 mg/L) and the remaining 12 isolates were highly resistant (MIC ≥ 16 mg/L) to the drug. Five resistant isolates did not harbor mutations in the known pretomanid resistant genes. CONCLUSIONS: Our results further support a breakpoint of 0.5 mg/L for a non-L1 MTB population, which is characteristic of China. Further, our data point to an unexpected high (14/475, 3%) pre-existing pretomanid resistance rate in the country, as well as to the existence of yet-to-be-discovered pretomanid resistance genes.

Epidemiology of tuberculosis among children in Beijing, China, 2012-2021.

Data on epidemiology trends of paediatric tuberculosis (TB) are limited in China. So, we investigated the clinical and epidemiological profiles in diagnosed TB disease and TB infection patients at Beijing Children's Hospital. Of 3 193 patients, 51.05% had pulmonary TB (PTB) and 15.16% had extrapulmonary TB (EPTB). The most frequent forms of EPTB were TB meningitis (39.05%), pleural TB (29.75%), and disseminated TB (10.33%). PTB patients were significantly younger and associated with higher hospitalization frequency. Children aged 1-4 years exhibited higher risk of PTB and TB meningitis, and children aged 5-12 years had higher risk of EPTB. The proportion of PTB patients increased slightly from 40.9% in 2012 to 65% in 2019, and then decreased to 17.8% in 2021. The percentage of EPTB cases decreased from 18.3% in 2012 to 15.2% in 2019, but increased to 16.4% in 2021. Among EPTB cases, the largest increase was seen in TB meningitis. In conclusion, female and young children had higher risk of PTB in children. TB meningitis was the most frequent forms of EPTB among children, and young children were at high risk of TB meningitis. The distribution of different types of EPTB differed by age.

Diagnostic value of tNGS vs Xpert MTB/RIF in childhood TB.

Objectives: To evaluate the diagnostic value of targeted next generation sequencing (tNGS) in childhood tuberculosis (TB) and compare the accuracy with Xpert MTB/RIF method. Methods: Children aged ≤18 years with symptoms suggestive of TB during July 2021 to December 2022 at Beijing Children's Hospital were included, and the performances of tNGS and Xpert were evaluated. Results: A total of 103 children with suspected TB were recruited, including 72 discharge diagnosis of TB and 31 non-TB cases. The mean age was 7.37 ± 4.77 years, and 62.1 % were male. The most common type of specimens was gastric aspirate (GA) (59, 57.3 %). Among all the 72 TB patients, tNGS showed higher sensitivity than Xpert, but the difference was not significant (34.7 %, 25/72 vs 20.8 %, 15/72; P = 0.063). The specificities of tNGS and Xpert were 87.1 % (27/31) and 96.8 % (30/31), respectively (P = 0.162). Among different types of specimen, the highest sensitivity of tNGS on sputum and pus was observed (80.0 %, 4/5), followed by pleural effusion (50.0 %, 2/4). One rifampin resistance and one protionamide resistance were detected in bacteriologically confirmed TB by tNGS. Conclusion: tNGS had a higher sensitivity but lower specificity compared to Xpert in diagnosis of children TB. tNGS yielded higher sensitivity than Xpert on gastric aspirate and sputum and pus.

Interferon-gamma release assay for screening of tuberculosis infection in children.

BACKGROUND: Interferon-gamma release assay (IGRA) is the main tool for the diagnosis of latent tuberculosis (TB) infection (LTBI). However, the indeterminate results were more frequent in children, and the underlying reasons were largely speculative. We aimed to compare QuantiFERON-TB Gold In-Tube (QFT-GIT) with X.DOT-TB (XDOT) for diagnosing LTBI, and to identify the risk factors associated with indeterminate results in children. METHODS: A retrospective study for children<18 years old, at risk for LTBI or progression to TB disease, received either QFT-GIT or X.DOT-TB tests was performed at Beijing Children's Hospital from August 2019 to August 2022. RESULTS: A total of 33,662 children were recruited, including 15,129 (44.9%) tested with X.DOT-TB and 18,533 (55.1%) with QFT-GIT. Proportion of positive and indeterminate results in children with respiratory disease was significantly higher than did that with other diseases, respectively (P < 0.001). The indeterminate rate of X.DOT-TB and QFT-GIT results decreased with increasing age (P < 0.001). Proportion of QFT-GIT indeterminate results was higher than that of X.DOT-TB across age groups. Male, age and disease classification all presented a statistically significant association with indeterminate IGRA results. CONCLUSIONS: The positive rates of X.DOT-TB and QFT-GIT in children were 3.1% and 1.8%, respectively. The X.DOT-TB assay performed better than QFT-GIT in children, and male, age and underlying diseases were associated with an increased risk of indeterminate IGRA results.

Bioprospecting for the soil-derived actinobacteria and bioactive secondary metabolites on the Western Qinghai-Tibet Plateau.

Introduction: The increase in incidence of multidrug-resistant bacteria and the inadequacy of new antimicrobial drugs have led to a widespread outbreak of bacterial antimicrobial resistance. To discover new antibiotics, biodiversity, and novelty of culturable actinobacteria dwelled in soil of the Western Qinghai-Tibet Plateau were investigated. By integrating antibacterial assay with omics tools, Amycolatopsis sp. A133, a rare actinobacterial strain and its secondary metabolites were further studied. Method: Culture-dependent method was used to obtain actinobacterial strains from two soil samples collected from Ali region in Qinghai-Tibet Plateau. The cultural extractions of representative strains were assayed against "ESKAPE" pathogens by paper-disk diffusion method and the double fluorescent protein reporter "pDualrep2" system. An Amycolatopsis strain coded as A133 was prioritized and its secondary metabolites were further analyzed and annotated by omics tools including antiSMASH and GNPS (Global Natural Social Molecular Networking). The predicted rifamycin analogs produced by Amycolatopsis sp. A133 were isolated and identified by chromatographic separation, such as Sephadex LH-20 and HPLC, and spectral analysis, such as NMR and UPLC-HRESI-MS/MS, respectively. Results: A total of 406 actinobacteria strains affiliated to 36 genera in 17 families of 9 orders were isolated. Out of 152 representative strains, 63 isolates exhibited antagonistic activity against at least one of the tested pathogens. Among them, 7 positive strains were identified by the "pDualrep2" system as either an inhibitor of protein translation or DNA biosynthesis. The cultural broth of Amycolatopsis sp. A133 exhibited a broader antimicrobial activity and can induce expression of TurboRFP. The secondary metabolites produced by strain A133 was annotated as rifamycins and zampanolides by antiSMASH and GNPS analysis. Five members of rifamycins, including rifamycin W, protorifamycin I, rifamycin W-M1, proansamycin B, and rifamycin S, were purified and identified. Rifamycin W-M1, was found as a new member of the naturally occurring rifamycin group of antibiotics. Discussion: Assisted by omics tools, the successful and highly efficient discovery of rifamycins, a group of clinically used antibiotics from actinobacteria in Ali area encouraged us to devote more energy to explore new antibiotics from the soils on the Western Tibetan Plateau.

Bioprospecting of Actinobacterial Diversity and Antibacterial Secondary Metabolites from the Sediments of Four Saline Lakes on the Northern Tibetan Plateau.

The Tibetan Plateau, known as the "Roof of the World" and "The Third Pole", harbors numerous saline lakes primarily distributed in the Northern Tibetan Plateau. However, the challenging conditions of high altitude, low oxygen level, and harsh climate have limited investigations into the actinobacteria from these saline lakes. This study focuses on investigating the biodiversity and bioactive secondary metabolites of cultivable actinobacteria isolated from the sediments of four saline lakes on the Northern Tibetan Plateau. A total of 255 actinobacterial strains affiliated with 21 genera in 12 families of 7 orders were recovered by using the pure culture technique and 16S rRNA gene phylogenetic analysis. To facilitate a high-throughput bioactivity evaluation, 192 isolates underwent OSMAC cultivation in a miniaturized 24-well microbioreactor system (MATRIX cultivation). The antibacterial activity of crude extracts was then evaluated in a 96-well plate antibacterial assay. Forty-six strains demonstrated antagonistic effects against at least one tested pathogen, and their underlying antibacterial mechanisms were further investigated through a dual-fluorescent reporter assay (pDualrep2). Two Streptomyces strains (378 and 549) that produce compounds triggering DNA damage were prioritized for subsequent chemical investigations. Metabolomics profiling involving HPLC-UV/vis, UPLC-QTOF-MS/MS, and molecular networking identified three types of bioactive metabolites belonging to the aromatic polyketide family, i.e., cosmomycin, kidamycin, and hedamycin. In-depth analysis of the metabolomic data unveiled some potentially novel anthracycline compounds. A genome mining study based on the whole-genome sequences of strains 378 and 549 identified gene clusters potentially responsible for cosmomycin and kidamycin biosynthesis. This work highlights the effectiveness of combining metabolomic and genomic approaches to rapidly identify bioactive chemicals within microbial extracts. The saline lakes on the Northern Tibetan Plateau present prospective sources for discovering novel actinobacteria and biologically active compounds.

Phycicoccus sonneraticus sp. nov., a Novel Endophytic Actinobacterium Isolated from the Bark of Sonneratia apetala.

A novel endophytic actinobacterial strain, designated MQZ13P-5T, was isolated from a piece of bark of Sonneratia apetala, collected from Guangxi Zhuang Autonomous Region, China. This strain was Gram-stain positive, aerobic, non-spore-forming, non-motile and rod-shaped. Comparative 16S rRNA gene sequence analysis showed that strain MQZ13P-5T was related to the genus Phycicoccus with exhibiting the highest similarity (98.0%) to Phycicoccus endophyticus IP6SC6T. The phylogenetic trees based on 16S rRNA gene sequences and core genes indicated that strain MQZ13P-5T belonged to the genus Phycicoccus and could not be assigned to any described species. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between strain MQZ13P-5T and type strains of Phycicoccus species were less than 84% and 27%, respectively, below the thresholds for species delineation. This strain showed chemotaxonomic and phenotypic properties consistent with its classification in the genus Phycicoccus. Based on the taxonomic data, strain MQZ13P-5T should represent a novel species of the genus Phycicoccus, for which the name Phycicoccus sonneraticus sp. nov. is proposed, with the type strain MQZ13P-5T (= CGMCC 1.18744T = JCM 34337T).

Performance of two interferon-gamma release assays for tuberculosis infection screening in Kawasaki children before immunosuppressive therapy.

Objective: We aimed to compare QuantiFERON-TB Gold In-Tube (QFT-GIT) and X.DOT-TB for screening latent tuberculosis infection (LTBI) in kawasaki patients, and to identify the risk factors associated with indeterminate IGRA results. Methods: We conducted a retrospective study on children with KD, who were screened for mycobacterium tuberculosis (Mtb) infection by either ELISA-based QFT-GIT or ELISPOT-based X.DOT-TB tests, admitted in Department of Cardiology, Beijing Children's Hospital from July 2019 to April 2022. Results: A total of 1327 cases were included. Among them, 932 cases were tested by QFT-GIT and 395 cases by X.DOT-TB. The positive rate of children was 0.1% and 0.2%, and the indeterminate rate was 68.2% and 6.1% for QFT-GIT and X.DOT-TB, respectively. Patients with hypoproteinemia had a higher risk of indeterminate X.DOT-TB result. Female, critical ill, shock or hypoproteinemia presented statistically significant associations with an increased risk of indeterminate QFT-GIT result. High-dose of IVIG inhibited the release of IFN-γ by more than 90%, which might account for the high indeterminate incidence. Conclusion: It is recommended to perform X.DOT-TB rather than QFT-GIT to screen LTBI in patients with high level of the mitogen that can inhibit IFN-γ release. For KD children with positive IGRA results, it has a higher risk of activation TB infection when treated with immunosuppressive therapy in the future. Children with KD aged <5 years old had higher frequency of indeterminate IGRA results.

Protaetiibacter mangrovi sp. nov., isolated from mangrove soil.

A novel Gram-stain-positive, aerobic, non-flagellated and rod-shaped actinobacterium, designated 10F1B-8-1T, was isolated from mangrove soil sampled at Futian Mangrove Nature Reserve, China. The isolate was able to grow at 10-40 °C (optimum 30-32 °C), at pH 6-8 (optimum 7) and in the presence of 0-6% (w/v) NaCl (optimum 0%). Strain 10F1B-8-1T shared the highest 16S rRNA gene sequence similarity to Protaetiibacter larvae NBRC 113051T (98.3%), followed by Protaetiibacter intestinalis NBRC 113050T (98.2%). Phylogenetic trees based on 16S rRNA gene sequences and the core proteomes exhibited that strain 10F1B-8-1T formed a new phyletic line in the clade of genus Protaetiibacter, indicating that this strain belonged to the genus Protaetiibacter. Strain 10F1B-8-1T showed low average nucleotide identity (<84%) and digital DNA-DNA hybridization values (<27%) with closely related taxa, suggesting that strain 10F1B-8-1T was a hitherto undescribed species of the genus Protaetiibacter. Strain 10F1B-8-1T contained D-2,4-diaminobutyric acid as the diagnostic diamino acid, and the peptidoglycan type was characterized as type B2ß. The major fatty acids were iso-C16:0, anteiso-C15:0 and anteiso-C17:0. The major menaquinones were MK-13 and MK-14. The polar lipid profile included diphosphatidylglycerol, phosphatidylglycerol, an unidentified glycolipid and five unidentified lipids. Notably, the ethyl acetate extracts of strain 10F1B-8-1T showed effective antibacterial activity against Bacillus subtilis CPCC 100029 and Escherichia coli △tolC. According to the polyphasic data, strain 10F1B-8-1T should be classified as a novel species of the genus Protaetiibacter, for which the name Protaetiibacter mangrovi sp. nov. is proposed, with the type strain 10F1B-8-1T (=JCM 33142T = CPCC 205428T).

Georgenia halotolerans sp. nov., a halotolerant actinobacterium isolated from Taklamakan desert soil.

A Gram-stain-positive, aerobic, non-motile, non-spore-forming and rod-shaped actinobacterium, designated strain 10Sc9-8T, was isolated from Taklamakan desert soil sampled in the Xinjiang Uygur Autonomous Region, China. Strain 10Sc9-8T grew at 8‒37 °C (optimum, 28‒30 °C), pH 6.0‒10.0 (optimum, pH 7.0-8.0) and in the presence of 0‒15 % (w/v) NaCl (optimum, 0-3 %). Phylogenetic analysis based on 16S rRNA gene sequence suggested that strain 10Sc9-8T was affiliated with members of the genus Georgenia and showed the highest 16S rRNA gene sequence similarity to Georgenia yuyongxinii Z443T (97.4 %). Phylogenomic analysis based on the whole genome sequences indicated that strain 10Sc9-8T should be assigned into the genus Georgenia. The average nucleotide identity and digital DNA-DNA hybridization values calculated from the whole genome sequences indicated that strain 10Sc9-8T was clearly separated from other closely related species of the genus Georgenia with values below the thresholds for species delineation. Chemotaxonomic analyses showed that the cell-wall peptidoglycan was in a variant of A4α type with an interpeptide bridge comprising l-Lys-l-Ala-Gly-l-Asp. The predominant menaquinone was MK-8(H4). The polar lipids comprised diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannoside, several unidentified phospholipids, glycolipids and one unidentified lipid. The major fatty acids were anteiso-C15 : 0, anteiso-C15 : 1 A and C16 : 0. The genomic DNA G+C content was 72.7 mol%. On the basis of phenotypic, phylogenetic and phylogenomic data, strain 10Sc9-8T represents a novel species of the genus Georgenia, for which the name Georgenia halotolerans sp. nov. is proposed. The type strain is 10Sc9-8T (=JCM 33946T=CPCC 206219T).

Ancylobacter mangrovi sp. nov., a novel endophytic bacterium isolated from mangrove plant.

Two novel strains GSK1Z-4-2T and MQZ15Z-1 were isolated from branches of mangrove plants collected from Guangxi Zhuang Autonomous Region, China. Both strains were Gram-negative, aerobic, non-flagellated and non-spore-forming bacteria. The comparison of 16S rRNA gene sequences initially indicated that the two strains were assigned to the genus Ancylobacter with sharing the highest similarity to Ancylobacter pratisalsi DSM 102029T (97.3%). The 16S rRNA gene sequence similarity, average nucleotide identity (ANI) and in silico DNA-DNA hybridization (isDDH) values between strains GSK1Z-4-2T and MQZ15Z-1 were 99.9%, 97.4% and 77.4%, respectively, which revealed that the two strains belonged to the same species. Phylogenetic analyses based on 16S rRNA gene sequences and the core proteome showed that the two strains formed a well-supported cluster with A. pratisalsi DSM 102029T. Moreover, the ANI and isDDH values between strain GSK1Z-4-2T and A. pratisalsi DSM 102029T were 83.0% and 25.8%, respectively, demonstrating that strain GSK1Z-4-2T was a previously undescribed species. Meanwhile, strains GSK1Z-4-2T and MQZ15Z-1 exhibited most of chemotaxonomic and phenotypic features consistent with the description of the genus Ancylobacter. Based on the polyphasic data, strains GSK1Z-4-2T and MQZ15Z-1 should represent a novel species of the genus Ancylobacter, for which the name Ancylobacter mangrovi sp. nov. is proposed. The type strain is GSK1Z-4-2T (=MCCC 1K07181T = JCM 34924T).

Paenibacillus mangrovi sp. nov., a novel endophytic bacterium isolated from bark of Kandelia candel.

A endospore-forming bacterium, designated strain KQZ6P-2T, was isolated from surface-sterilized bark of the mangrove plant Kandelia candel, collected from Maowei Sea Mangrove Nature Reserve in Guangxi Zhuang Autonomous Region, China. Strain KQZ6P-2T was able to grow at NaCl concentrations in the range of 0-3 % (w/v) with optimum growth at 0-1 % (w/v) NaCl. Growth occurred at 20-42 °C (optimal growth at 30-37 °C) and pH 5.5-6.5 (optimal growth at pH 6.5). The 16S rRNA gene sequence similarity between strain KQZ6P-2T and its closest phylogenetic neighbour Paenibacillus chibensis JCM 9905T was 98.2 %. Phylogenetic analyses using 16S rRNA gene sequences showed that strain KQZ6P-2T formed a distinct lineage with Paenibacillus chibensis JCM 9905T. The draft genome of strain KQZ6P-2T was 5 937 633 bp in size and its DNA G+C content was 47.2mol%. Comparative genome analysis revealed that the average nucleotide identity, digital DNA-DNA hybridization and average amino acid identity values among strain KQZ6P-2T and its related species were below the cut-off levels of 95, 70 and 95.5%, respec-tively. The cell-wall peptidoglycan of strain KQZ6P-2T contained meso-diaminopimelic acid as the diagnostic diamino acid. Major cellular fatty acids were anteiso-C15:0 and C16:0. The polar lipids comprised diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, two unidentified aminophospholipids, four unidentified phospholipids, an unidentified aminolipid and five unidentified lipids. Based on phylogenetic, phenotypic and chemotaxonomic data, strain KQZ6P-2T represents a novel species of the genus Paenibacillus, for which the name Paenibacillus mangrovi sp. nov. is proposed. The type strain is KQZ6P-2T (=MCCC 1K07172T =JCM 34931T).

Investigation of bedaquiline resistance and genetic mutations in multi-drug resistant Mycobacterium tuberculosis clinical isolates in Chongqing, China.

BACKGROUND: To investigate the prevalence and molecular characterization of bedaquiline resistance among MDR-TB isolates collected from Chongqing, China. METHODS: A total of 205 MDR-TB isolates were collected from Chongqing Tuberculosis Control Institute between March 2019 and June 2020. The MICs of BDQ were determined by microplate alamarblue assay. All strains were genotyped by melting curve spoligotyping, and were subjected to WGS. RESULTS: Among the 205 MDR isolates, the resistance rate of BDQ was 4.4% (9/205). The 55 (26.8%) were from male patients and 50 (24.4%) were new cases. Furthermore, 81 (39.5%) of these patients exhibited lung cavitation, 13 (6.3%) patients afflicted with diabetes mellitus, and 170 (82.9%) isolates belonged to Beijing family. However, the distribution of BDQ resistant isolates showed no significant difference among these characteristics. Of the 86 OFX resistant isolates, 8 isolates were XDR (9.3%, 8/86). Six BDQ resistant isolates (66.7%, 6/9) and two BDQ susceptible isolates (1.0%, 2/196) carried mutations in Rv0678. A total of 4 mutations types were identified in BDQ resistant isolates, including mutation in A152G (50%, 3/6), T56C (16.7%, 1/6), GA492 insertion (16.7%, 1/6), and A274 insertion (16.7%, 1/6). BDQ showed excellent activity against MDR-TB in Chongqing. CONCLUSIONS: BDQ showed excellent activity against MDR-TB in Chongqing. The resistance rate of BDQ was not related to demographic and clinical characteristics. Mutations in Rv0678 gene were the major mechanism to BDQ resistance, with A152G as the most common mutation type. WGS has a good popularize value and application prospect in the rapid detection of BDQ resistance.

Bioprospecting of desert actinobacteria with special emphases on griseoviridin, mitomycin C and a new bacterial metabolite producing Streptomyces sp. PU-KB10-4.

BACKGROUND: Bioprospecting of actinobacteria isolated from Kubuqi desert, China for antibacterial, antifungal and cytotoxic metabolites production and their structure elucidation. RESULTS: A total of 100 actinobacteria strains were selectively isolated from Kubuqi desert, Inner Mongolia, China. The taxonomic characterization revealed Streptomyces as the predominant genus comprising 37 different species, along with the rare actinobacterial genus Lentzea. The methanolic extracts of 60.8% of strains exhibited potent antimicrobial activities against Staphylococcus aureus, Micrococcus luteus, Bacillus subtilis, Escherichia coli, Salmonella enterica, Saccharomyces cerevisiae and high to mild in vitro cytotoxicity against PC3 (prostate cancer) and A549 (lung carcinoma) cell lines. The metabolomics analysis by TLC, HPLC-UV/vis, HPLC-MS and NMR showed the presence of compounds with molecular weights ranging from 100 to 1000 Da. The scale-up fermentation of the prioritized anti-Gram-negative strain PU-KB10-4 (Streptomyces griseoviridis), yielded three pure compounds including; griseoviridin (1; 42.0 mgL- 1) with 20 fold increased production as compared to previous reports and its crystal structure as monohydrate form is herein reported for the first time, mitomycin C (2; 0.3 mgL- 1) and a new bacterial metabolite 4-hydroxycinnamide (3; 0.59 mgL- 1). CONCLUSIONS: This is the first report of the bioprospecting and exploration of actinobacteria from Kubuqi desert and the metabolite 4-hydroxycinnamide (3) is first time isolated from a bacterial source. This study demonstrated that actinobacteria from Kubuqi desert are a potential source of novel bioactive natural products. Underexplored harsh environments like the Kubuqi desert may harbor a wider diversity of actinobacteria, particularly Streptomyces, which produce unique metabolites and are an intriguing source to develop medicinally valuable natural products.

Description and genomic characterization of Nocardioides bruguierae sp. nov., isolated from Bruguiera gymnorhiza.

Strains BSK12Z-3T and BSK12Z-4, two Gram-stain-positive, aerobic, non-spore-forming strains, were isolated from Shankou Mangrove Nature Reserve, Guangxi Zhuang Autonomous Region, China. The diagnostic diamino acid in the cell-wall peptidoglycan of strain BSK12Z-3T was LL-diaminopimelic acid and MK-8(H4) was the predominant menaquinone. The polar lipids comprised diphosphatidylglycerol (DPG), phosphatidylglycerol (PG) and phospholipid (PL). The major fatty acids was iso-C16:0. Phylogenetic analysis based on 16S rRNA gene sequences suggested that the two strains fell within the genus Nocardioides, appearing most closely related to Nocardioides ginkgobilobae KCTC 39594T (97.5-97.6 % sequence similarity) and Nocardioides marinus DSM 18248T (97.4-97.6 %). Genome-based phylogenetic analysis confirmed that strains BSK12Z-3T and BSK12Z-4 formed a distinct phylogenetic cluster within the genus Nocardioides. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values of strains BSK12Z-3T, BSK12Z-4 with their most related species N. marinus DSM18248T were within the ranges of 77.2-77.3 % and 21.3-21.4 %, respectively, clearly indicated that strains BSK12Z-3T, BSK12Z-4 represented novel species. Strains BSK12Z-3T and BSK12Z-4 exhibited 99.9 % 16S rRNA gene sequence similarity. The ANI and dDDH values between the two strains were 97.8 % and 81.1 %, respectively, suggesting that they belong to the same species. However, DNA fingerprinting discriminated that they were not from one clonal origin. Based on phylogenomic and phylogenetic analyses coupled with phenotypic and chemotaxonomic characterizatons, strains BSK12Z-3T and BSK12Z-4 could be classified as a novel species of the genus Nocardioides, for which the name Nocardioides bruguierae sp. nov., is proposed. The type strain is BSK12Z-3T (=CGMCC 4.7709T = JCM 34554T).

Jiella avicenniae sp. nov., a novel endophytic bacterium isolated from bark of Avicennia marina.

A Gram-stain-negative and short rod-shaped strain CBK1P-4T, isolated from surface-sterilized bark of Avicennia marina was investigated by a polyphasic taxonomic approach to resolve its taxonomic position. Strain CBK1P-4T grew at 10-30 °C (optimum, 25 °C), pH 5.0-9.0 (optimum, pH 5.5) and in the presence of 0-9% (w/v) NaCl (optimum, 1-2%). Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain CBK1P-4T belonged to the genus Jiella and was most closely related to species of the genus Jiella (97.4-98.3%). The genome comparisons between strain CBK1P-4T and the closely related species indicated that average nucleotide identity and digital DNA-DNA hybridization values were below the recommended thresholds for assigning strains to the same species (95-96% and 70%, respectively). The cell wall peptidoglycan contained meso-diaminopimelic acid as diagnostic diamino acid. The principal fatty acids were C18:1ω7c and C19:0cycloω8c. The polar lipids were mainly comprised of phosphatidylcholine, diphosphatidylglycerol, phosphatidylglycerol, phosphatidylmonomethylethanolamine, phosphatidylethanolamine, two unidentified aminolipids, one unidentified phospholipid and one unidentified glycolipid. The dominant respiratory quinone was ubiquinone-10. The DNA G + C content of strain CBK1P-4T was 66.7%. Based on the phenotypic features, phylogenetic analysis as well as genome analysis, we conclude that strain CBK1P-4T represents a novel Jiella species, for which the name Jiella avicenniae sp. nov. is proposed. The type strain is CBK1P-4T (= CGMCC 1.18742T = JCM 34330T).

Development of a Rapid and Efficient RPA-CRISPR/Cas12a Assay for Mycoplasma pneumoniae Detection.

Mycoplasma pneumoniae (MP) is a one of most common pathogen in causing respiratory infection in children and adolescents. Rapid and efficient diagnostic methods are crucial for control and treatment of MP infections. Herein, we present an operationally simple, rapid and efficient molecular method for MP identification, which eliminates expensive instruments and specialized personnel. The method combines recombinase polymerase amplification (RPA) with clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR associated proteins (Cas) 12a-based detection, with an optimal procedure less than 1 h from sample to result including DNA extraction (25 min), RPA reaction (39°C for 15-20 min), CRISPR/Cas12a detection (37°C for 10 min) and visual detection by naked eyes (2 min). This diagnostic method shows high sensitivity (two copies per reaction) and no cross-reactivity against other common pathogenic bacteria. Preliminary evaluation using 201 clinical samples shows sensitivity of 99.1% (107/108), specificity of 100% (93/93) and consistency of 99.5% (200/201), compared with real-time PCR method. The above data demonstrate that our developed method is reliable for rapid diagnosis of MP. In conclusion, the RPA-CRISPR/Cas12a has a great potential to be as a useful tool for reliable and quick diagnosis of MP infection, especially in primary hospitals with limited conditions.

Stakelama flava sp. nov., a novel endophytic bacterium isolated from a branch of Kandelia candel.

A Gram-stain-negative, aerobic, motile, non-spore-forming, short-rod-shaped strain that did not produce diffusible pigment, designated CBK3Z-3T, was isolated from a branch of Kandelia candel, collected from the Beilun Estuary National Nature Reserve in Guangxi Zhang Autonomous Region, PR China, and investigated by a polyphasic approach to determine its taxonomic position. Strain CBK3Z-3T grew at pH 5.0-10.0 (optimum, pH 8.0), 20-37 °C (optimum, 25-30 °C) and with 0-10 % (w/v) NaCl (optimum, 2-3 %). Phylogenetic analysis based on 16S rRNA gene sequences showed that strain CBK3Z-3T was closely related to species of genus Stakelama and had the highest 16S rRNA gene sequence similarity of 98.7 % to Stakelama pacifica CGMCC 1.7294T. The DNA G+C content value of strain CBK3Z-3T was 62.6 mol%. The diagnostic diamino acid in the cell-wall peptidoglycan was meso-diaminopimelic acid and the polar lipids comprised diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, sphingoglycolipid, an unidentified aminolipid and an unidentified lipid. The major fatty acids were C18 : 1 ω7c and C16 : 0. The average nucleotide identity, estimated digital DNA-DNA hybridization and average amino acid identity values between strain CBK3Z-3T and the type strain of Stakelama pacifica CGMCC 1.7294T were 80.4, 23.1 and 81.5 %, respectively. Based on the phylogenetic, phenotypic and chemotaxonomic data, strain CBK3Z-3T should be designated as a novel species of the genus Stakelama, for which the name Stakelama flava sp.nov. is proposed. The type strain is CBK3Z-3T (=JCM 34534T=CGMCC 1.18972T).